<template>
  <div class="score-case">
    <div class="table">
      <table>
        <thead>
          <tr>
            <th>编号</th>
            <th>科目</th>
            <th>成绩</th>
            <th>考试时间</th>
            <th>操作</th>
          </tr>
        </thead>
        <!-- 遍历form表单，渲染函数 -->
        <tbody v-if="this.list.length">
          <tr v-for="item in list" :key="item">
            <td>{{item.id}}</td>
            <td>{{item.subject}}</td>
            <!-- 判断成绩是否及格不及格变红 -->
            <td :class="{red:item.score<60}">{{item.score}}</td>
            <td>{{formatDate(item.data)}}</td>
            <td><a href="#" @click.prevent="add(item.id)">删除</a></td>
          </tr>
        </tbody>
        <tbody v-else>
          <tr>
            <td colspan="5">
              <span class="none">暂无数据</span>
            </td>
          </tr>
        </tbody>
        <tfoot>
          <tr>
            <td colspan="5">
              <span>总分：{{sum}}</span>
              <span style="margin-left:50px">平均分:{{(sum / list.length).toFixed(2)}}</span>
            </td>
          </tr>
        </tfoot>
      </table>
    </div>
    <div class="form">
      <div class="form-item">
        <div class="label">科目：</div>
        <div class="input">
          <input type="text" placeholder="请输入科目" v-model.trim="subject">
        </div>
      </div>
      <div class="form-item">
        <div class="label">分数：</div>
        <div class="input">
          <input type="text" placeholder="请输入分数"  v-model.number.trim="score">
        </div>
      </div>
      <div class="form-item">
        <div class="label"></div>
        <div class="input">
          <button class="submit"  @click="fn">添加</button>
        </div>
      </div>
    </div>
  </div>
</template>

<script>
//引入moment插件
import moment from 'moment'

export default {
  name: 'ScoreCase',
  data () {
    return {
      // 字符转转对象
      list:JSON.parse((localStorage.getItem('subjectList')) ) || [
        {id: 1, subject: '语文', score: 89, date: new Date('2022/06/07 10:00:00')},
        {id: 2, subject: '数学', score: 100, date: new Date('2022/06/07 15:00:00')},
        {id: 3, subject: '英语', score: 56, date: new Date('2022/06/08 10:00:00')},
        {id: 4, subject: '物理', score: 76, date: new Date('2022/06/08 10:00:00')}
      ],
      subject: '',
      score: ''
    }
  },
  methods: {
    // 绑定添加事件
    fn() {
         this.list = [...this.list,  {
          id: this.list.length + 1, 
          subject: this.subject, 
          score: this.score, 
          date: new Date()
        }
      ]
    //清空输入框
      this.subject = ''
      this.score = ''
    },
    // 绑定删除事件
    add(id) {
       this.list= this.list.filter(item =>  item.id !== id)
    },
     //插值表达式第二种，可以使用methods中的函数，但是要有效果的话一定要return出结果
    formatDate(date) {
        return moment(date).format('YYYY-MM-DD HH:mm:ss')
    }
  },
//   conputed 要写在export default里面和data同级
   computed:{
    //定义求和函数
    sum () {
      return this.list.reduce((prev,item) => prev + item.score,0)
    }
  },
  // 侦听器
  watch:{
    list:{
      deep:true,
      handler( ) {
        // 对象转字符串
        localStorage.setItem('subjectList',JSON.stringify(this.list))
      }
    }
  }
};
</script>

<style lang="less">
.score-case {
  width: 1000px;
  margin: 50px auto;
  display: flex;
  .table {
    flex: 4;
    table {
      width: 100%;
      border-spacing: 0;
      border-top: 1px solid #ccc;
      border-left: 1px solid #ccc;
      th {
        background: #f5f5f5;
      }
      tr:hover td {
        background: #f5f5f5;
      }
      td,
      th {
        border-bottom: 1px solid #ccc;
        border-right: 1px solid #ccc;
        text-align: center;
        padding: 10px;
        &.red {
          color: red;
        }
      }
    }
    .none {
      height: 100px;
      line-height: 100px;
      color: #999;
    }
  }
  .form {
    flex: 1;
    padding: 20px;
    .form-item {
      display: flex;
      margin-bottom: 20px;
      align-items: center;
    }
    .form-item .label {
      width: 60px;
      text-align: right;
      font-size: 14px;
    }
    .form-item .input {
      flex: 1;
    }
    .form-item input,
    .form-item select {
      appearance: none;
      outline: none;
      border: 1px solid #ccc;
      width: 200px;
      height: 40px;
      box-sizing: border-box;
      padding: 10px;
      color: #666;
    }
    .form-item input::placeholder {
      color: #666;
    }
    .form-item .cancel,
    .form-item .submit {
      appearance: none;
      outline: none;
      border: 1px solid #ccc;
      border-radius: 4px;
      padding: 4px 10px;
      margin-right: 10px;
      font-size: 12px;
      background: #ccc;
    }
    .form-item .submit {
      border-color: #069;
      background: #069;
      color: #fff;
    }
  }
}
</style>